Antitubercular, rifamycin derivative
ATC code: J04AB04 (Rifabutin)
Brand names
Mycobutin
Inhibits DNA-dependent RNA polymerase of mycobacteria and bacteria. Spectrum is similar to rifampicin, but CYP3A4 induction is 2-3 fold weaker – hence preferred with antiretrovirals and immunosuppressants. Additional advantage – activity against Mycobacterium avium complex.
Second line
Rifabutin is second-line antitubercular in standard 4-drug regimen (replacing rifampicin) in HIV-positive patients on ART or transplant recipients. 2024 recommends rifabutin when rifampicin causes unacceptable drops in co-administered drug levels.
Sources
3 pairs found. Sorted from critical to minor.
Mechanism
Rifabutin is a moderate CYP3A4 + P-gp inducer (2-3 fold weaker than rifampicin). Apixaban falls 30-40%. Lower risk than with rifampicin but still significant.
Symptoms
Reduced anticoagulation, thrombosis risk.
Management
If possible – warfarin to INR 2.0-3.0.
Mechanism
Clarithromycin inhibits CYP3A4. Rifabutin rises 2.5-fold – increased uveitis risk, especially in MAC infection patients.
Symptoms
Eye pain, photophobia, reduced vision.
Management
Reduce rifabutin to 300 mg/day (standard 450 mg). Regular ophthalmology review.
Mechanism
Ritonavir inhibits CYP3A4. Rifabutin rises 4-fold – severe neutropenia and uveitis risk. 2024 recommends reducing rifabutin to 150 mg three times weekly.
Symptoms
Neutropenia, uveitis within 2-4 weeks.
Management
Reduce rifabutin to 150 mg three times weekly. Weekly CBC for first month.
Opens the checker prefilled with this drug. Pick the second one from your regimen.
Used when necessary. Safety better studied outside pregnancy.
Passes into milk. Breastfeeding possible with infant monitoring.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Rifabutin is evaluated for the following indications with varying evidence strength: Drug-susceptible tuberculosis (evidence tier A). See the full indication matrix with dosing and citations above on this page.
Common side effects of Rifabutin (≥ 1 in 100): Orange discoloration of body fluids, Nausea, Rash, Neutropenia, Transaminase rise. See the Safety section for uncommon and serious reactions.
FDA category B. Used when necessary. Safety better studied outside pregnancy.
Passes into milk. Breastfeeding possible with infant monitoring.
Rifabutin is contraindicated in: Rifamycin hypersensitivity; Active uveitis; Combination with delavirdine, rilpivirine. Full list in the Safety section.